Altaic etymology :

Comments:A Kor.-Jpn. isogloss. See Martin 241, АПиПЯЯ 297 (with some confusion of Kor. *kǝ̀čh 'exterior' and *kằč- 'near; end, limit', see under *kĕ̀č`á, *k`i̯ŏ́ǯa). The root seems very similar to both *kĕ̀č`á and *k`i̯ŏ́ǯa, but in fact cannot be reduced to either of them. It is not even excluded that the root does not exist at all: Kor. kǝ̀čh 'exterior side' may be just a variant of kàčh 'skin' (see under *káč`u), while Jpn. kátà may go back to PA *k`ada 'side, to turn' (q. v.).